As soon as news broke that Kate Middleton, 31, was in labor Monday morning, celebrities took to Twitter to express their excitement about the royal baby's arrival. The Duchess of Cambridge was taken to the private Lindo Wing of St. Mary’s Hospital in west London's Paddington neighborhood at 6 a.m. with Prince William by her side.

According to reports, Middleton will be giving birth naturally and was not induced into labor. No one knows the sex of the royal baby, including the Duchess and Prince William, making the British royal birth that much more exciting. After her arrival at the hospital, a spokesperson confirmed that everything is going well. "Things are progressing as normal," they said.

The birth will not be made public until the royal family is briefed, and the royal baby -- boy or girl -- will be third in line for the throne. As the sex of the baby is not known, some celebrities made their own predictions. Journalist Piers Morgan, for one, decided both the sex and the name of the royal baby.